Boston’s first mascot for mass transit was a horse named Old Billy. By far the best known of the city’s 8,000 streetcar horses before electricity, he achieved international attention for his longevity and durability. Old Billy labored 30 years, logged more than 125,000 miles, and never took a sick day, before enjoying a decade of semi-retired celebrity.

Dina Rudick/Globe Staff

Charlie, the new mascot for the MBTA.

The MBTA’s newest mascot, a plush character named Charlie who debuted Wednesday, is a show horse, not a workhorse. Without peripheral vision, he needed a team of handlers to avoid falling onto the tracks or getting hit by a car on his first day. He also took frequent hydration breaks, ducking out of sight to remove a giant felt head that sealed in the summer heat.

That Charlie was doomed to ride forever ’neath the streets of Boston. The new Charlie puttered on and off the bus and subway in oversized shoes, roaming among tourist sites (State House, Swan Boats, Fenway Park) and busy stations to promote the T and dispense reloadable plastic CharlieCards bearing his visage.

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Some greeted him as a celebrity. “I hugged Charlie! My life’s complete,” Swan Boat driver Kyle Swardstrom, 17, declared, pumping both fists. Near Fenway, a waitress dashed from Boston Beer Works to snag a photo with Charlie, and a group of 6- to 8-year-olds from Charlestown’s Boys & Girls Club mobbed him, seeking his autograph on their freshly issued CharlieCards.

Others kept their distance or stared only when they thought Charlie was not looking. Mostly, he drew puzzled looks.

“Inspector Gadget?” several asked. Though Charlie’s hat was not yellow, other said, “I know, the man from Curious George.”

T officials may have over­estimated the recognizability of the cheerful-looking character in the gray fedora. Charlie wears no logo, not even an ­MBTA pin.

“Jimmy? Johnny?” a man on Brookline Avenue guessed. Handed a CharlieCard, he only looked puzzled.

Even some anticipating Charlie were confused.

“What is the mascot?” a television reporter, new to the area, asked Massachusetts Bay Transportation Authority spokesman Joe Pesaturo.

“Charlie,” Pesaturo said.

“I know, Charlie from the CharlieCard,” the reporter said. “But what is he? Just a guy?”

“He’s more than a guy, he’s an ambassador of goodwill,” ­Pesaturo said.

The T went through this when it introduced the paper CharlieTicket and the plastic CharlieCard, but the question lingers. Few under 60 or who have not logged time at a campfire singalong know Charlie.

Adding to the lack of recognition Wednesday, even those who know the song may have their own mental picture of Charlie. Although 7 million CharlieCards have been distributed, few study his cartoon face while tapping their card at a fare gate.

Also, people do not expect to see a mascot for public transit, much less on public transit. When Charlie boarded the Green Line at Arlington, a man seated nearby studied him warily. Others shot video — from the next car over.

When the trolley stopped at Copley, a group of Japanese tourists waiting on the platform sprang to life, giving Charlie thumbs up, waving, hopping, and snapping photos.

Charlie’s arrival was not timed for anything in particular, the recent fare increase notwithstanding. The marketing team decided last year it would be fun to have a costumed mascot promote transit at occasional public events. They found a sponsor, Mass Bay Credit Union, to contribute $5,000, enough for the costume and a photographer to document Charlie’s first day.

The only other cost is staff time. The 26-year-old marketing employee drafted to wear the suit for reasons of youth, size, and stamina (he declined to be named, preserving ­Charlie’s everyman quality and his own dignity) was followed by three co-workers. They carried his bag, kept him plied with water, answered questions, tended reporters, handed maps to the public, and supplemented Charlie’s pin-prick eyes.

Outside the State House, David Wood, normally a T graphic designer, pointed ­Charlie toward a family of four hovering nearby. “Want a picture with Charlie?” he asked. A girl in a Snoopy shirt took a step back. “He won’t bite,” ­Pesaturo said.

After appearances at South Station, a branch of the sponsoring credit union, and Downtown Crossing, Charlie retreated to headquarters, where his head was stashed in a protective blue duffle bag, his suit hung on a hook in the marketing warren.

Charlie’s fate, as the song goes, is still unknown, but it will doubtless be different than that of Old Billy. After the horse died on Christmas 1891 — some said he was 42, others 46 — his skeleton was willed to the precursor to the Museum of Science. Records show he was accessioned July 16, 1892, but he has not been seen in years.

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